The field of the present invention is calendars and calculation of time periods.
Attorneys, construction and production supervisors and managers, and other professions find themselves repeatedly calculating periods of time in days, weeks and months either forwardly or backwardly for purposes of establishing a date at some increment of time from a given starting date, or of counting days or weeks between dates, and needing to know the day of the week of the found date. These calculations can be critical in terms of deadlines, imposed under rules, contractual obligations and the like. Difficulties in such calculations result from unequal months, the lack of an even division of weeks during leap year.
Calendars provide an inconvenient method for such calculation, particularly for longer periods of time. Electronic means may be employed using electronically stored data, but such a system is unnecessarily complicated, is likely to be expensive and is naturally subject to failure.